Styrene derivatives useful as herbicides and defoliants

Abstract

Abstract of the Disclosure: Styrene derivatives I ogen, R3 is H, halogen or C1-C4-alkyl, R4 is CN or C1-C6-alkylcarbonyl and A is a heterocyclic radical A1 to A5: <IMAGE> A1 <IMAGE> A2 <IMAGE> A3 <IMAGE> A4 <IMAGE> A5 where R5 and R6 are H, CH3 or C2H5, n is 0 or 1 and X is oxygen or sulfur, with the proviso that R4 is alkylcarbonyl when R1 is H and at the same time A is A2 where n is 0, and agriculturally useful salts thereof, processes for the preparation of the styrene derivatives I and herbicides containing them.

We claim: 
     
       1. A styrene derivative of the formula I ##STR48## where R 1  is hydrogen or halogen, R 2  is halogen, R 3  is hydrogen, halogen or C 1  -C 4  -alkyl, R 4  is cyano or C 1  -C 6  -alkylcarbonyl and A is a heterocyclic radical selected from the groups A 1  to A 5  ##STR49## where R 5  and R 6  are each hydrogen, methyl or ethyl, n is 0 or 1 and X is oxygen or sulfur, with the proviso that n is 0, R 1  is hydrogen or fluorine, R 2  is chlorine, R 3  is chlorine, and R 4  is methylcarbonyl when A is the radical A 2  or agriculturally useful salts thereof. 
     
     
       2. A method for the defoliation of cotton, wherein the cotton plants are treated with an effective amount of a styrene derivative of the formula I ##STR50## where R 1  is hydrogen or halogen, R 2  is halogen, R 3  is hydrogen, halogen or C 1  -C 4  -alkyl, R 4  is cyano or C 1  -C 6  -alkylcarbonyl and A is a heterocyclic radical selected from the groups A 1  to A 5  ##STR51## where R 5  and R 6  are each hydrogen, methyl or ethyl, n is 0 or 1 and X is oxygen or sulfur, with the proviso that R 4  is C 1  -C 6  -alkylcarbonyl when R 1  is hydrogen and at the same time A is the radical A 2  where n is 0, or agriculturally useful salts thereof. 
     
     
       3. A herbicide containing conventional inert additives and at least one styrene derivative of the formula I as claimed in claim 1. 
     
     
       4. A method for controlling undesirable plant growth, wherein the undesirable plants or their habitat are or is treated with a herbicidal amount of a styrene derivative of the formula I as claimed in claim 1.